Snap-action closures have been proposed for use on containers, and a number of such closures are commercially available today. Such closures typically include a base, collar, or body for being mounted on the container and for defining an opening into the container. Also, such a closure typically includes a lid, cap, or cover hingedly mounted to the base, collar, or body for movement between a closed position and an open position.
In conventional snap-action closures, the snap-action is provided through an arrangement of one or more main hinges and one or more offset connecting links. In some closures designs, the connecting links project or hang downwardly below the cover when the cover is in the open position. This can be aesthetically undesirable. Further, such a condition increases the exposure of the usually delicate connecting link to accidental, and possibly deleterious, interference or contact with exterior ambient objects.
Further, some conventional closures employ hinge and/or connecting link structures that define relatively large projections on the closure when the cover is in the closed position. This can interfere with the proper operation of certain types of conventional automatic closure-applying equipment. Further, such projections are frequently aesthetically undesirable.
Other conventional closure designs, in an attempt to reduce exterior projections, employ recessed structures and configurations. Such conventional closures typically require a relatively large amount of interior space to accommodate the recessed configuration. This tends to reduce the amount of usable internal volume in the closure and can effect the design of the interior portion of the closure structure that mounts on the container. Also, some closures with recessed configurations necessarily define or present concave openings in the exterior of the closure. These concave openings may communicate with the interior of the closure and can thus permit ingress of contaminants. Further, such concave openings may be aesthetically undesirable and/or act as sites for dirt accummulation.
Some designs for snap-action closures would appear to at least theoretically provide the desired snap-action operation. However, in practice, when such designs are incorporated in actual container closures fabricated from conventional materials, such as thermoplastic materials and the like, the operation of the closure is not entirely satisfactory. It has been found that some of these closures do not generate a snap-action that is as strong as would be desired.
It has also been found that some of these closures are relatively unstable and too flexible when the cover is in the open position. That is, the cover can too easily be twisted in one or more directions when it is in the open position and as it is moved to the closed position. When such closures are fabricated from conventional thermoplastic materials, the closure, during or after such cover twisting, may take on a temporary set that inhibits proper closing of the cover in precise registry with the body.
In view of the above-discussed problems with conventional snap-action closures, it would be desirable to provide an improved snap-action closure having increased resistance to twisting when the closure cover is in the open position.
Further, it would be desirable to provide such a closure with the capability for operating with a relatively forceful snap-action to insure complete and proper closing of the cover.
Also, it would be beneficial if such an improved closure employed a structure in which the connecting links would not project or hang downwardly below the cover when the cover is in the open position.
Finally, such an improved closure should advantageously have a configuration in the closed position that is substantially free of projections or features that might interfere with some types of conventional automatic capping machines. In this regard, a closure having substantially no interfering exterior projections should also have a configuration with a relatively large interior usable space. That is, it would be advantageous if the structures employed to effect the snap-action of the improved closure did not project too far inwardly so as to interfere with potential use of the interior region of the closure.